Anatomical And Cytological Observation Of Upland Cotton Allogeneic Male Sterile Line

Cotton is an important economic crop with significant heterosis.With the increasing demand for cotton in modern economic society,the value of cotton research has become more important.The cotton heterosis utilization of my country was conducted from the 1990 s.Which not only has important value for understanding the plant genetic mechanism but also laid a foundation for the utilization of plant heterosis.But so far,hybrid cotton has not been wildly cultivated.Which is attributed to single cytoplasm,few restoring lines,and weak heterosis,and the negative effect of cytoplasmic.Therefore,discovering new germplasm resources of cotton sterile is still the main problem that must be solved for cotton heterosis.In this study,six homogenous heteronuclear cytoplasmic male sterile lines with different cytoplasmic sources selected by professor Zhou were used as materials.And the size and cytological of different development of flower buds were detected.The main results were as followed:1.Through the observation of 6 different cotton cytoplasmic male sterile lines,it was found that the pollen abortion of these 6 isoplasmic allonuclear CMS lines all began in the pollen mother cell stage,and completely aborted in the tetrad stage.The abortion characteristics of Zhong16 S,276S,07-113 S,J-4S,NS11-10 S,H06S are shown as follows: at the pollen mother cell stage,the microspore mother cell develops normally,the nucleus is large and the cytoplasm is very dense,the four layers cell walls are tightly arranged and the structure is clear and complete;at the tetrad stage,the microspores began to degrade,the nucleus was dissolved,showing vacuolation,but the tapetum layer was still tightly connected to other cell walls without any change.It was found that no tetrad microspores were observed.At the early Uninucleate stage,with the degradation of the microspores,penetration of nucleus through cell membrane and cell wall in pollen sac can be observed,and it would become a half-moon shape after degradation.Following the disintegration of the microspores,only part of the corpus callosum remained in the pollen sac.At the late Uninucleate stage,the degraded microspores were dispersed in the sac,the nucleus was highly vacuolated,and the middle layer didn’t degenerate;the subsequent microspores were degraded,and it was found that there were plasmodesmata in the pollen sac,and only a small amount of residue left;at the mature pollen grains stage,the tapetum layer began to grow radially,without pollen grains in the pollen sac and then shrinked inward into a solid shape.2.Through anatomical research on the anther tapetum of these 6 cotton CMS lines,the results showed that the tapetum cell structure was intact and arranged at the sporogenous cell stage.There were no abnormalities in the compact,epidermal layer,middle layer,and endothelial layer.The structure was complete and clear,and the arrangement was regular.The pollen mother cells in the pollen sac were wrapped by the darker callose.Later,at late Uninucleate stage,the tapetum layer appeared puffing,leaving a small amount of residue after disintegration.There was no streak-like wood thickening on the inner wall of the medicine chamber,and the middle layer didn’t degrad normally.However,at the mature pollen grains stage,it was found that C3 Echang 2A in 07-113 S was abnormal,and the middle layer had serious expansion.It was speculated that the middle layer developed further and caused expansion.Subsequently,as the tapetum cells in the pollen sac continued to elongate and expand,squeeze the cavity,and finally became a peripheral mass.